Exhaust hood with UVC light assembly

ABSTRACT

An exhaust hood is provided for filtering pollutants from exhaust air. The exhaust hood includes a light assembly and an air blower assembly for generating a stream of air in front of the light assembly.

This application claims the benefit of U.S. Provisional Application No.60/473,151, filed May 27, 2003, the disclosure of which is herebyincorporated by reference in its entirety, as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an exhaust hood whichutilizes ultraviolet light to decontaminate exhaust air.

2. Description of the Related Art

In a number of work environments, such as kitchens and laboratories,exhaust hoods are used to vent exhaust air containing grease, fat,odors, and other pollutants. (hereinafter referred to as “pollutants”)produced by the utilization of cooking or heating appliances (ranges,ovens, stoves, burners, etc.). The exhaust hoods are positioned abovethe appliances, where a fan draws and directs exhaust air to an exhaustoutlet. Before reaching the exhaust outlet, the exhaust air is drawnthrough at least one filter, such as a baffle filter or cartridgefilter. The filter removes large particles of the pollutants from theexhaust air, leaving small particles in the exhaust air, such as greasevapor.

The exhaust hood may also have a mesh filter. The exhaust air exitingthe mechanical filter enters the mesh filter which removes even smallerparticles of pollutants before the exhaust air enters the exhaustoutlet.

To avoid grease buildup in the hood and exhaust system, exhaust hoodsmay also use ultraviolet lights, typically in the “C” wavelength range(known in the art as “UVC lights”). FIGS. 1A, 1B, and 2 depictconventional exhaust hoods with UVC lights.

FIG. 1A shows an exhaust system manufactured by HALTON, in which exhaustair including grease vapor & particulate enters a hood 100 along with asupplemental supply of air, capture jet air curtain, 123. The exhaustair combined with the jet air curtain enters a cartridge, a KSAcartridge, 104 and flows past a bank of UVC lights 107, controlled by aballast/control unit 201, before being exhausted to the atmospherethrough a clean exhaust duct and hood chamber 105. The exhaust systemalso includes an optional make up air duct 120, a capture jet fan andair intake 121, and an optional low velocity front discharge plenum (200feet per minute) 122.

FIG. 1B depicts a system manufactured by VENT MASTER, in which exhaustair comprising grease particulate and grease vapor enters a hood 100.The exhaust air circulates through a filter 104 which removes the greaseparticulate from the exhaust air. The exhaust air with grease vaporsflows past a bank of ultraviolet lights 107, causing a chemicalreaction, described in more detail below. Entering the clean duct work105, is the exhaust air exposed to UVC light and O³ (ozone).

A detailed description of how conventional exhaust hoods with UVC lightsoperates follows. FIG. 2 shows a cross-sectional view of exhaust hood100.

Exhaust hood 100 includes a housing 101 having a rear wall 102, a frontwall 103 spaced from the rear walls. Exhaust hood 100 is positionedabove the appliance 106. Exhaust hood 100 also includes a filter 104,positioned between exhaust fan 108/exhaust outlet 105 and the exhaustinlet 109. As discussed above, the exhaust hood may also use a secondaryfiltration mechanism, such as a mesh filter 202, which is positionedbetween the filter 104 and the exhaust outlet 105. Exhaust hood 100 mayalso include a light assembly housing a plurality of UVC lights 107controlled by a conventional UVC ballast/control unit 201, together orin place of the mesh filter 202. As shown in FIGS. 1 and 2, the UVClights 107 are installed between the filter 104 and the exhaust outlet105 in a generally horizontal position, such that when the exhaust airexits the filter 104 and, if applicable, the mesh filter 202, theexhaust air passes in front of the UVC lights 107. A resulting chemicalreaction converts, for example, some of the grease and fat molecules inthe exhaust air into water, carbon dioxide, and mineral acids. Theseby-products are then drawn out through the exhaust outlet 105. The UVClights 107 may also be installed in a generally vertical position alongthe rear wall 102 of the exhaust hood 100, as shown in FIG. 3. FIG. 3also shows lamp 221 used to illuminate the cooking area.

The exhaust air is also partially deodorized by the chemical reactionbecause small particles of pollutants which causes odors, are removed.

Conventional exhaust hoods with UVC lights, as described above, havedrawbacks. As shown in FIGS. 1 and 2, the UVC lights 107 are positioneddirectly in the path of the exhaust air. Thus, “dirty” exhaust air, thatis, containing grease, fat, etc. passes over the bulbs of the UVC lights107, forming a coating of pollutants on the bulbs. This reduces theefficiency of the ultraviolet lights, and when the UVC light bulbs arecompletely covered, they are no longer capable of removing pollutantsfrom the exhaust air. Similarly, when the UVC lights 107 are positionedalong the rear wall 102 of the exhaust hood 100 (see FIG. 3), greasevapors adhere to the UVC bulbs, again reducing the efficiency of the UVClights to remove pollutants. Consequently, to maintain the efficiencyand functionality of the UVC lights 107, they must be periodicallycleaned. For example, expensive, quarterly maintenance cleaning of theUVC bulbs by a qualified technician may be required.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus toovercome the drawbacks of conventional exhaust hoods with UVC flights.

In order to achieve the above object, according to one aspect of thepresent invention, an apparatus is provided that includes a lightassembly, and an air blower assembly for generating a stream of air infront of the light assembly.

According to another aspect of the present invention, a method ofremoving pollutants from exhaust air is provided. The method includesthe steps of drawing exhaust air through a filter, causing a chemicalreaction between ultraviolet rays emitted from a light assembly and thepollutants in the exhaust air, and directing a stream of air in front ofthe light assembly.

Further objects, features, and advantages of the present invention willbecome apparent from the following description of the preferredembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross-sectional views of a cooking environment,depicting conventional exhaust hoods with UVC lights;

FIG. 2 is a cross-sectional view of a conventional exhaust hood with UVClights positioned in a generally horizonal direction;

FIG. 3 is a cross-sectional view of a conventional exhaust hood with UVClights positioned in a generally vertical direction;

FIG. 4 is a cross-sectional view of an embodiment of the presentinvention;

FIG. 5 is a cross-sectional view of another embodiment of the presentinvention;

FIG. 6 corresponds to the exhaust hood of FIG. 4, showing preferreddimensions; and

FIG. 7 corresponds to the exhaust hood of FIG. 5, showing preferreddimensions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4 is a cross-sectional view of an exhaust hood 400 according to anembodiment of the invention. Exhaust hood 400 has a rear wall 401 and afront wall 402 and two side walls (not shown) connecting the front andrear walls. Attached to the bottom of the rear wall is a bracket 403extending forward in a substantially horizontal direction towards thefront wall 402. An exhaust collar 406 extends upward from the ceiling405 of the exhaust hood 400 and is attached to an exhaust fan 408. Theexhaust fan 408 draws the exhaust air generated by an appliance (notshown) into the exhaust collar 406. Attached to the exhaust fan 408 isan exhaust duct 407 for venting the exhaust air out into, for example,the atmosphere. Attached to the bottom of the front wall 402 is anoptional heat shield 410 which extends in a substantially horizontaldirection towards the rear wall 401. The heat shield 410 preventscirculating exhaust air within the exhaust hood chamber 411 from exitingunderneath the front wall 402 of the exhaust hood 400. Located withinthe exhaust hood chamber 411, between the exhaust collar 406 and theappliance, is a filter 404, such as a baffle filter or a cartridgefilter, removing particles of pollutants from the exhaust air as theexhaust air is drawn through the filter 404. One end of the filter 404is held by the bracket 403. The other end of the filter 404 is held tothe ceiling member 405 by bracket 413.

As further shown in FIG. 4, a light assembly 414 having at least onelight bulb, preferably an ultraviolet light bulb emitting ultravioletrays having a wavelength of between 1 and 310 nanometers, is locatedalong the inside of the rear wall 401 within the exhaust hood chamber411, in a substantially vertical position, such that it is not withinthe direct path of the exhaust air. Further, the light assembly 414 ispositioned so that the filter 404 prevents ultraviolet rays emitted fromthe light assembly 414 from escaping the exhaust hood chamber 411. Thelight assembly 414 is attached to the rear wall 401 by bracket 415 andis controlled by a ballast/control unit 416.

Exhaust hood 400 also includes an air chamber 417 located above theceiling member 405 and along the length of the rear wall 401. The airchamber terminates near the bottom of the rear wall 401 with an outletopening 419 in a substantially upward direction, past the front of thelight assembly 414. Fan or air blower 420 is communicatively attached tothe end of the air chamber 417, above the ceiling member 405. Fan or airblower 420 generates a stream of clean air that travels through the airchamber 417, through outlet opening 419, and in front of light assembly414, thereby creating a “wall” of clean air between the “dirty” exhaustair and the light assembly 414. This, in turn, substantially reduces theamount of pollutants that adhere to the light bulbs.

Exhaust hood 400 also includes an optional lamp 421 that is used toilluminate the hood chamber 411 and the appliance.

The exhaust hood 400 operates as follows. Exhaust air containingpollutants is created by normal operation of the appliance. To vent theexhaust air away from the appliance, an exhaust hood 400 is positionedabove the appliance. The exhaust fan 408, attached to the exhaust duct407 and the exhaust collar 406, draws the exhaust air away from theappliance into the exhaust hood chamber 411.

Exhaust air is drawn through the filter 404, which removes particles ofpollutants from the exhaust air. Exiting the filter 404, the exhaustair, still containing pollutants (usually as vapor), is exposed to theultraviolet rays from a light assembly 414, which further treats theexhaust air before venting it into, for example, the atmosphere. Thatis, additional pollutants and odors are removed from the exhaust air bya chemical reaction between the pollutants and ultraviolet rays emittedfrom light assembly. The by-products of this chemical reaction and thetreated exhaust air are drawn out from the exhaust hood chamber 411 intothe exhaust collar 406 and the exhaust duct 407.

To minimize contact between the “dirty” exhaust air and the light bulbsof the light assembly 414, the wall of clean air, generated by the fanor blower 420, is discharged from the air chamber 417 through the outletopening 419 in front of the light assembly 414, thereby separating thelight assembly 414 from the exhaust air. The wall of clean air is ventedout from the exhaust hood chamber 411, through the exhaust collar 406and the exhaust duct 407, in a similar manner as the treated exhaustair.

By providing the wall of clean air between the light assembly 414 andthe exhaust air, pollutants and contaminants in the exhaust air aresubstantially prevented from coming into contact with light assembly414. Thus, any coating of the light bulbs is minimized, and theefficiency and functionality of the light assembly 414 is maintainedover a much longer period of time than in a conventional exhaust hood.Further, expensive periodic cleaning of the UVC lights is minimized, ifnot eliminated outright.

Another embodiment of the present invention is to provide a secondoutlet opening 418 at the end of the air chamber 417, as shown in FIG.5. The operation of the second embodiment is substantially similar asthat of the exhaust hood 400 in the first embodiment, with the exceptionof the second outlet opening 418. The second outlet opening 418 ispositioned such that a second stream of clean air exiting opening 418 isintroduced behind the light assembly 414. This second stream of cleanair flows upwards in a substantially vertical direction, where itcollides with the bracket 415, which redirects it across the front oflight assembly 414, where it combines with the wall of clean air fromthe outlet opening 419.

The second stream of clean air pressurizes the back of the lightassembly 414 so that grease vapor is substantially prevented frommigrating towards the light assembly 414. This is especially useful whenhaving to vent a great amount of exhaust air containing large volumes ofpollutants.

FIGS. 6 and 7 respectively correspond to the exhaust hoods of FIGS. 4and 5, showing preferred dimensions. However, as will be appreciated bythose skilled in the art, these dimensions may vary.

While the present invention has been described with reference to whatare considered to be the preferred embodiments, it is to be understoodthat the invention is not limited to the disclosed embodiments. On thecontrary, the invention is intended to cover various modifications andequivalent arrangements included within the spirit and scope of theappended claims. For example, while this invention has been described inconnection with exhaust hoods, it may be applied in other apparatuses inwhich one desires to separate a light assembly from a “dirty” stream ofair. Accordingly, the scope of the following claims is to be accordedthe broadest interpretation so as to encompass all such modificationsand equivalent structures and functions.

1. An apparatus comprising: a light assembly; and an air blower assemblyfor generating a stream of air in front of the light assembly.
 2. Anapparatus according to claim 1, wherein the light assembly comprises oneor more ultraviolet light bulbs.
 3. An apparatus according to claim 2,wherein the one or more ultraviolet light bulbs emit ultraviolet rays inthe “C” wavelength range of ultraviolet light.
 4. An apparatus accordingto claim 1, further comprising: a hood for housing the light assemblyand the air blower assembly, wherein the hood has front, rear, and sidewalls, and a ceiling.
 5. An apparatus according to claim 1, wherein theair blower assembly comprises a fan and an air chamber communicativelyconnected thereto, wherein the air chamber directs the stream of air infront of the light assembly.
 6. An apparatus according to claim 5,wherein the air chamber has an opening to discharge the stream of air infront of the light assembly.
 7. An apparatus according to claim 6,wherein the air chamber has a second opening to discharge a secondstream of air behind the light assembly.
 8. An apparatus comprising: ahood positioned above a cooking surface, wherein the hood has front,rear, and side walls, and a ceiling; an exhaust collar creating anopening in the ceiling of the hood; a first fan attached to the exhaustcollar, for drawing exhaust air from the hood into an exhaust ductpositioned above the exhaust collar; a filter for filtering the exhaustair, positioned between the exhaust collar and the cooking surface; alight assembly positioned between the exhaust collar and the filter; asecond fan for producing a first stream of clean air; an air intakechamber communicatively connected at a first end to the second fan, theair intake chamber having an opening at a second end for discharging thefirst stream of clean air in front of the light assembly.
 9. Anapparatus according to claim 8, wherein the air intake chamber has asecond opening at the second end for discharging a second stream ofclean air behind the light assembly.
 10. An apparatus according to claim9, wherein the second stream of clean air is redirected to the front ofthe light assembly, and combines with the first stream of clean air. 11.An apparatus according to claim 8, wherein the light assembly comprisesone or more ultraviolet light bulbs.
 12. An apparatus according to claim11, wherein the one or more ultraviolet light bulbs emit ultravioletrays in the “C” wavelength range of ultraviolet light.
 13. An apparatusaccording to claim 11, wherein the filter blocks ultraviolet rays fromescaping from the exhaust hood.
 14. A method of substantially removingpollutants from exhaust air, the method comprising the steps of: drawingexhaust air through a filter; causing a chemical reaction betweenultraviolet rays emitted from a light assembly and the pollutants in theexhaust air; and directing a first stream of clean air in front of thelight assembly.
 15. A method according to claim 14, further comprising astep of directing a second stream of clean air behind the lightassembly.
 16. A method according to claim 15, further comprising thestep of redirecting the second stream of clean air to the front of thelight assembly, and combining with the first stream of clean air.
 17. Amethod according to claim 14, wherein the filter blocks the ultravioletrays from escaping from the exhaust hood.